This project has a major objective the development of pertinent information and data on (1) chemicals nominated to the NTP for various types of toxicological testing and (2) chemicals previously tested by the NTP for one or more toxicological endpoints, as well as their structural analogs, which may be candidates for further NTP testing. The project consists of three tasks: Task 1: The contractor shall provide technical support to the Office of the Assisstant to the Director, NTP, in the evaluation of chemicals nominated for NTP toxiocological testing by preparing 50 Executive Summaries per year on the chemicals following nomination, and by incorporating data into the Summaries following each stage of the evaluation process. Task 2: The contractor shall develop summary information and data on chemicals previously tested by the NTP for one or more toxic endpoints and on structural analogs of such chemicals to aid NTP staff in determining which of these chemicals may be candidates for further NTP testing. The contractor will perform 10 such class studies per year. Task 3: The contractor shall collect, summarize, and enter relevant information and data on norminated chemicals into the NTP CHEMTRACK "On-line" data base for use in preparing the "NTP Chemical Nomination and Selection Report".